Changes for page Trigger Howto

Last modified by sndueste on 2023/07/07 11:28

From 9.1 to 10.1 From 19.1 to 20.1

From version 10.1

edited by sndueste
on 2019/09/17 14:29

Change comment: There is no comment for this version

To version 19.1

edited by sndueste
on 2020/01/23 09:29

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@@ -5,15 +5,36 @@
  = Introduction (user panel)
   =
--The MTCA based triggers have a jitter in the few ps range, the delay can be shifted in 1 ns steps (over many ms), one can choose between 10 Hz triggers, frequencies locked to the pulses (e.g. 1MHz) and the actual bunch patterns. A detailed description can be found in [[x2Timer manual>>attach:x2Timer.pdf]].
++The MTCA based triggers have a jitter in the few ps range, the delay can be shifted in 9 ns steps, One can choose between 10 Hz triggers, Triggers connected to the (fast) FEL shutters,  frequencies locked to the pulses (e.g. 1MHz) and the actual bunch patterns. A detailed description can be found in [[x2Timer manual>>attach:x2Timer.pdf]] ([[Design Paper>>url:http://ttfinfo2.desy.de/doocs/Timing/CDRv2.2short.pdf||shape="rect"]]).
--in short: the triggers are for low impedance (~~50 OHM terminated ?? ), 5V triggers with an adjustable width. The main control panel for the x2 timer has the control options for the 3 front modules (connected with a RJ45 cable - connecting to a "trigger box" with 2 trigger exits (Lemo) each) and 8 Lemo exits at the back of the crate. in the BL-beamline case these triggers are connected to the BNC (patch panel) ports at the rack.
++In short:
--The main control can be done with a simplified user panel which can handle the timing in respect to the FEL pulses and not in respect to some (arbitrary) reference time ( Event)[[~[~[image:url:http://hasfweb.desy.de/pub/Setup/TriggerHowto/Trigger_scheme.gif~|~|alt="Trigger_scheme.gif" width="800"~]~]>>attach:Trigger_scheme.gif]]
++* the triggers are for low impedance (~~50 Ohm )
++* signal level is + 5V - otherwise 0V (in the expert panel one can also invert the signal - base line is +5 V and trigger 0V)
++* The trigger are send to the MTCA several ms before the first FEL pulse (3.1 ms for the "standard" trigger, 23 ms for the "early" trigger).
++* The timer card can delay the trigger in 9 ns  steps for more than 100 ms (an option to shift the trigger in 1 ns steps is available in the expert panel)
++* The shown delay in µs is in respect to the //first// FEL pulse. negative delay: trigger comes before FEL, positive : trigger comes after the FEL.
++* The desired delay has to be entered in the "delay to be set" field and as second step pressing the "set delay" sends the delay value to the timer card. Then the trigger delay will be changed and the "actual delay" will be updated.
++* The trigger can be set to only provide a trigger signal if the FEL Fast shutter is open. One has to choose which FEL shutter to use.
++* The trigger  width can be adjusted from 9 ns to several ms in 9 ns steps
++* The timer card can in addition to the 10 Hz triggers also provide frequencies which are linked to the FEL repetition rate and the actual burst pattern of the FEL. For details how to set these modes see below
++* At the beamlines the triggers are provided with a  BNC patch panel
++The main control can be done with a simplified user panel which can handle the timing in respect to the FEL pulses (and not in respect to some arbitrary event time)
++
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  = Different trigger events (starting points) =
  one can configure each channel for an individual trigger event
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  = Expert panels =
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  = Set a constant frequency to a channel =
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++== General FLASH frequencies: ==
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++(% class="relative-table wrapped" style="width: 19.422%;" %)
++|(% class="highlight-grey" title="Hintergrundfarbe : Grau" data-highlight-colour="grey" %)(((
++(% style="color: rgb(0,0,0);" title="" %)**Name
++**
++)))|(% class="highlight-grey" title="Hintergrundfarbe : Grau" data-highlight-colour="grey" %)(((
++(% style="color: rgb(0,0,0);" title="" %)**Frequency
++**
++)))|(% class="highlight-grey" title="Hintergrundfarbe : Grau" data-highlight-colour="grey" %)(((
++(% style="color: rgb(0,0,0);" title="" %)**Divider**
++)))
++|(((
++1.3 GHz
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++1300.000000 MHz
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++)))
++|(((
++108 MHz
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++108.333333 MHz
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++9 MHz
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++9.02777777 MHz
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++4.5 MHz
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++4.513888 MHz
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++288
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++1 MHz
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++1.003086 MHz
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++1296
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  Once a clock is configured with the right frequency one can choose in the "expert panel" of the according channel the "FPGA clock" in the "input source select"  chooser.
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  One has to set the delay to values less than the repetition rate ... (so for 1 MHz between 0 and 990 µs)  and the trigger width also less than the rep rate ...
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++This results in a continuous train of pulses with the set trigger width.
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++= Creating an (own) burst trigger =
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++One can use now a SECOND trigger channel which is set to a regular 10 Hz trigger  and gate the clock output to create a burst with defined start point and length,
--This results in a continuous train of pulses with the set trigger width :
++For the example we use the FRONT.TRG2 (BL3 Trg5) as gate pulse which defines the length of the burst (set with the trigger width) and the (rough) starting point of the burst. This trigger is only used as gate and the physical trigger output is NOT used.
--= Creating an (own) burst trigger =
++The  second channel (here FRONT.TRG3 (BL3 Trg6) which is set to the clock frequency defines the reprate (by the FPGA clock setting) , the exact starting point of the first trigger ( by the delay ) and the width of the  MHz/kHz triggers (width).
--One can use now a SECOND trigger channel which is set to a regular 10 Hz trigger  and gate the clock output to create a burst with defined start point and length,
++**To get from the clock to the burst trigger** one has to:
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++* set the  "2nd source select" to the gate trigger ( here FRONT.TRG2) - this defines a second source to considder for the trigger output.
++* and the "output source select" to "AND 2nd Ch."  this finally only sends a trigger if on both inputs (clock and gate) we have a high signal.
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++[[image:attach:image2019-9-17_14-35-5.png||height="250"]]                        [[image:attach:image2019-9-17_14-34-38.png||width="400"]]
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++= Real bunch trigger  - get a trigger for each FEL pulse =
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--* in order to generate a stable frequency one has to set the input source to FPGA clock (and use dividers to get the desired frequency)
--* to generate the burst patterns of the FEL one has to choose a trigger event (best 116 for FLASH 2 and 16 for FLASH1) and activate Destination 1 for FLASH1 and Destination 2 for FLASH2 . finally one has to assign the activated Bunch pattern mask to the trigger channel of choice . now the pattern can be shifted and the trigger width can be changed as with the 10 Hz triggers. **IMPORTANT: to move the bunchtrain to the desired starting point the DELAY in the expert panel (see below) has to be used. The Trigger in the user panel (see above) has to be set to 0 !!!**
--[[~[~[image:url:http://hasfweb.desy.de/pub/Setup/TriggerHowto/mtcatrigger2k.png~|~|alt="mtcatrigger2k.png" width="607" height="458"~]~]>>attach:mtcatrigger2k.png]]
++Sometimes it is convenient to get a trigger pulse for each pulse in the FEL. thus if the FEL number of bunches or reprate are changed, the trigger adapts accordingly.
--here an example defining the bunch pattern for FLASH1 to mask 1
++For this one has to select the source of interest in the expert overview panel (tab: "Bunch pattern") ... well for us this is FLASH1 (FL1D) or FLASH2 (FL2D)
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++There are 6 different bunch pattern "channels" one can configure. Typically only 2 are needed ... And in each one there are 6 selectors to choose sources . We only need one - it does not matter in which one is used.
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++[[~[~[image:attach:image2019-9-17_14-51-28.png~|~|height="250"~]~]>>attach:image2019-9-17_14-51-28.png]][[image:attach:image2019-9-17_14-47-15.png||thumbnail="true" height="199"]]
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++In the expert panel one can now choose the configured "Bunch Pattern" as "Input source select"
++**NOTE: To shift the burst in time one can no longer use the delay of the individual channel BUT the delay in the "Bunch pattern" tab in the expert overview! This now shifts all bursts ... so you better know what you are doing. typically the burst is already shifted to the actual FEL timing ... Shifting the timing should be discussed with the beamline scientist / local contact ...**
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++[[image:attach:image2019-9-17_15-4-47.png||height="250"]][[image:attach:image2019-9-17_14-52-40.png||height="250"]]
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